I'm sure you'd be able to upgrade it, the question is what would you be charged? For example if you bought an ex-DOH AONE3 in Australia at DOH prices and then tried to upgrade in in, say, HKG to an AONE4, would the extra price be the difference between AONE4(ex-Aus) and the AONE3, or AONE4(ex-DOH)-AONE3(ex-DOH). I suspect they'd try to get you for the former since the point of sale was Australia.